Signaling the breakup of its U.S. operations, Arthur Andersen LLP announced Thursday that a "significant" number of its U.S. tax partners and professionals will join rival Deloitte & Touche.

Terms were not disclosed.

Andersen's U.S. operations have been jeopardized by the Enron Corp. scandal. The firm, which was the auditor for the bankrupt energy giant, hopes to survive as a slimmed-down company.

Andersen's U.S. tax services bring in between $750 million and $1 billion a year in revenue, according to Arthur Bowman, editor of the industry publication Bowman's Accounting Report. About a quarter of Andersen's 28,000 U.S. workers are in the tax group.

"This transaction is fully consistent with our commitment to move quickly on the Andersen reforms initiated by Mr. Volcker," said Larry Gorrell, managing partner of Arthur Andersen, the U.S. arm of Andersen Worldwide.

Former Federal Reserve Chairman Paul Volcker is head of an oversight board trying to reform Andersen and keep it alive as an independent firm.

Andersen's employees, meanwhile, were bracing for what the company has said would be "inevitable" layoffs among its 28,000 U.S. staffers. Spokesman Patrick Dorton, responding to persistent reports that layoffs could total 6,000 or more, said late Thursday that no final decision has been made.

Andersen said it had signed a memorandum of understanding with Deloitte that serves as an agreement in principle.

Andersen has 1,700 U.S. partners in tax, consulting and audit services. It was not clear how many would leave under the deal. Andersen said details remain to be worked out but it anticipates a closing date as soon as April 30.

"Our clients, partners and employees have been and will remain our priorities through this process of reforming and rebuilding Arthur Andersen LLP as a firm focused on quality auditing," Gorrell said.

Deloitte said in a statement, "Adding professionals from Andersen will add considerable talent to Deloitte & Touche's already high quality practice and gives us the opportunity to accelerate the growth" of that division.

The announcement followed weeks of negotiations between Andersen and other Big Five accounting firms over its assets. The company has been trying to sell assets to raise money, but previous efforts snagged over the issue of liability for the many lawsuits Andersen faces from its role as chief auditor for bankrupt Enron.

A federal grand jury indicted Andersen's U.S. arm March 14 on a charge of obstruction of justice for allegedly destroying documents related to its audit work for Enron. Andersen has lost dozens of clients in the ensuing weeks.

Arthur Bowman, editor of the industry publication Bowman's Accounting Report, said the company desperately needs cash to stay in business.

"It's probably the best thing they could do for their people and the firm itself, because as tax season ended these people would be looking for jobs elsewhere anyway," he said. "It's better to sell it as a unit and get revenue."

But he said the sale is a formal acknowledgment that the U.S. operations of once-mighty Andersen are breaking up. The firm has 1,700 U.S. partners in tax, consulting and audit services.

Andersen's overseas affiliates have also begun splitting off to merge with rival accounting firms.

Earlier Thursday, Andersen Worldwide named the chairman of its board of partners as acting chief executive, with the key task of trying to manage an orderly dismemberment of the firm's overseas operations.

Aldo Cardoso succeeds Joe Berardino, who resigned last week as head of both Andersen Worldwide and the firm's U.S. arm.